Micromechanical gyroscopic transducers which are micromachined from single unitary substrates such as single crystal or polycrystalline silicon or quartz are now well known in the art. Such micromechanical gyroscopes have the potential for achieving high sensitivity and reliability at the low cost of a mass produced device.
An exemplary gyroscopic transducer fabricated from a semiconductor wafer is disclosed in U.S. Pat. No. 5,016,072 entitled "Semiconductor Chip Gyroscopic Transducer" assigned to the assignee of the present invention.
The design of such devices seeks to optimize the performance of the device within the design constraints imposed by the choice of materials, while retaining a cost advantage.
Among the performance demands are a high signal to noise ratio in the readout or sense circuitry of the gyroscope. This high signal noise is a function of the capacitance between the stationary electrodes and the moving plate from which rate information is available. The signal to noise ratio is improved by having the largest capacitance possible and the largest change in that capacitance with rate. This translates into larger and closely spaced electrode plates.